System of waterborne units for dredging purposes

ABSTRACT

The invention provides a system of waterborne units for dredging purposes and comprises a dredger unit consisting of a relatively small self-powered vessel having normal ship form but with the forepart squared-off above the water-line, a stern propulsion and navigating unit the forepart whereof terminates at a flat bulkhead, and at least two hopper bow units the aft ends whereof terminate at flat sterns or bulkheads. The dredger unit and either of the two hopper bow units may be coupled and navigated for dredging operations, and the stern propulsion unit and either of the hopper bow units may be coupled and navigated as a unitary vessel for the rapid disposal of spoil. Box type hopper barges may be provided for interposing between the above referred to navigable arrangements of units.

United States Patent Stockdale [451 Mar. 21, 1972 [54] SYSTEM OF WATERBORNE UNITS FOR DREDGING PURPOSES [21] Appl.No.: 11,081

[30] Foreign Application Priority Data Primary Examiner-Trygve M. Blix Attorney-Linton & Linton [57] ABSTRACT The invention provides a system of waterborne units for dredging purposes and comprises a dredger unit consisting of a relatively small self-powered vessel having normal ship form but with the forepart squared-off above the water-line, a stern propulsion and navigating unit the forepart whereof ter- Feb. 13, 1969 Great Britain ..7,797/69 minates at a flat bulkhead, and at least two hopper bow units the aft ends whereof terminate at flat stems or bulkheads. The [52] U.S. Cl. ..114/235 R dredge; i and either f the two hopper bow units may be [5 l] Illlt. Cl ..B63b 21/00 coupled and navigated for dredging operations and the stem [58] Fleld of Search ..1 14/235; 37/54; propulsion unit and either of the pp bow units y be coupled and navigated as a unitary vessel for the rapid [56] defences cued disposal of spoil. Box type hopper barges may be provided for UNITED STATES PATENTS interposing between the above referred to navigable arrangements of units. 3,125,059 3/1964 Verneaux et al ..1 14/235 3,417,721 12/1968 Vienna ..l14/235 X 3 Claims, 5 Drawing Figures I a 1' i E 1 I I A l \l\l PATENTEUHAR 21 I972 SHEET 1 [)F 2 INVENTORZ GEOFFREY STOCKDRLE A Tro/ZNCVS PAIENTEDHARZ] I972 3,650,238

sum 2 0F 2 INVENTOR GEOFFREY STOCKDALE LQQKT QWM ATTORNEYS SYSTEM OF WATERBORNE UNITS FOR DREDGING PURPOSES This invention relates to dredging as carried out for example to maintain waterways in a navigable state and has for its object to provide a novel and efficient system of waterborne units which will enable a dredging operation to be effected with maximum efficiency insofar as use of equipment and power is concerned.

As will be appreciated, a conventional combined hopper and dredger vessel is generally uneconomical in use due to the fact that the greater part of its useful life may be, and usually is, spent not in dredging but in carrying spoil to a disposal point and returning from such disposal point after dumping the spoil. To reduce the dredging cycle time, powerful and expensive pumping and other dredging equipment is usually employed.

Further, even if such a dredger is maintained in operation, and the spoil therefrom discharged into separate hoppers or barges, these latter require to be towed by a tugboat, or a powered barge or hopper, to and from the disposal point, which is a slow and expensive operation and depends to a great extent upon suitable weather conditions.

According to the present invention, and in one mode of embodiment, a system of waterborne units for dredging purposes comprises, a dredger unit consisting of a relatively small selfpowered vessel having a normal ship form but with the forepart being squared off above the waterline, a stern propulsion and navigating unit the forepart whereof terminates at a fiat bulkhead, and at least two hopper bow units the aft ends whereof terminate in flat transom or sloping sterns or bulkheads.

The stern propulsion unit comprises steering and propulsion means, a navigating position and crews quarters, and the bulkhead thereof and the bulkheads or transom stems of the hopper bow units are such that the stern propulsion unit and either of the bow units may be connected and navigated in the manner of a conventional vessel of unitary hull design.

Also, the squared off bow of the dredger unit may also be connected to the flat stern of either of the hopper bow units so as to permit of the thus formed composite vessel being navigated and controlled appropriately during dredging operations. The propulsion means of the dredger unit need only be of sufficient power for dredging purposes while the propulsion means of the stern propulsion unit may be relatively high powered so that high transit speeds may be achieved during the dumping part ofa dredging cycle.

The means for connecting the various units in operable and navigable association may be of any suitable type and usually need be at deck level only. Examples of connecting means which may be used are described in prior English Pat. Nos. 902,908 and 922,313.

If desired, there may be provided for connection between the hopper bow units and the stern propulsion unit, or to the dredger unit, additional load carrying units of box type, i.e., hoppers or barges which are squared off at each end.

The invention is further described with the aid of the accompanying drawings which illustrate schematically, and by way of example only, one embodiment thereof.

In said drawings:

FIG. 1 is a side elevation of a dredger unit in operable association with a hopper bow unit, and

FIG. 2 is a plan view thereof.

FIG. 3 is a side elevation of a hopper bow unit coupled to the stern propulsion unit, and

FIG. 4 is a plan view thereof.

FIG. 5 is a view similar to that of FIG. 3 but illustrating a box-type hopper unit interposed between the stern propulsion and the hopper bow unit.

Referring to said drawings, the letter D (FIGS. 1 and 2) generally denotes a dredger unit, B a hopper bow unit, and S (FIGS. 3 and 4) a stern propulsion unit.

As will be observed the dredger unit D has a stern suction pipe controlled by lifting gear 1 l and a forwardly extending discharge pipe 12 arranged so as to discharge spoil, dredged up by the suction pipe 10, into the hopper bow unit B. The forepart or stem of the dredger unit D is carried out square above the waterline as at I3 in order that it may be operatively connected as by hinged coupling means 14 to the squared off stem 15 of said hopper bow unit B. The latter is provided with bottom doors 16 which may be opened, e.g., hydraulically, in conventional or other fashion so as to discharge spoil loaded into the hopper space 19 of the unit B. The discharge pipe 12 is arranged so as to discharge into so-called landers 17 of the bow unit B whereby the spoil is led by ducts 18 into the hopper space 19.

The stem propulsion unit S includes steering means in the form of a rudder 32 and propulsion means in the form of a propeller 33 driven from a power unit 34, navigating means and crews quarters, and comprising a flat forward bulkhead 20 for being secured as by hinged coupling means 21 at deck level to the squared off stem 15 of a hopper bow unit B.

In use, the dredger D (FIGS. 1 and 2) which has a rudder 35 and a propeller 36 driven by a power unit 37 operates with its dredging equipment 10, 11 preferably, but not necessarily, arranged at its stern. Spoil discharged from the pipe 12 is directed forwardly into the hopper space 19 of the bow unit B, and when the latter is full it is disconnected from the dredger unit D for replacement by a similar bow unit B. The full bow unit B is connected by the coupling means 21 to the stern propulsion unit S, as shown in FIGS. 3 and 4, and navigated to the disposal point. As the composite vessel comprising the stern propulsion unit S and the load carrying bow unit B may be operated and navigated in the manner more or less of conventional unitary hull vessel, even in rough sea conditions, its

design can be such as to enable speeds of 14 to 15 knots to be achieved.

The dredger unit D may of course be fitted with cranes and grabs or bucket-type dredging means in lieu of suction means as before described, and in such cases it may be more convenient for the dredging means to be arranged forwardly of the dredging unit.

It will be seen that with a dredging system as described, i.e., comprising a dredger unit D, at least two hopper bow units B, and a stern propulsion unit S, the dredging unit D can be maintained in substantially full-time operation with a consequence that the dredging apparatus itself may be of a less powerful nature, and he therefore less expensive, than is normally considered essential while maintaining an overall output comparable with a high powered unit employed in conventional manner.

Further, the spoil loaded into the hopper bow units can be disposed of by a shuttle system operated at relatively high speeds by the stern propulsion unit S. A high rate of efficiency can thus be obtained due to full use being made of all the available equipment, and the time taken for the return of empty hopper bow units B after discharge of their contents can be reduced to a minimum by virtue of the relatively high speeds which the composite hull vessels S, B may readily be designed to achieve.

If desired, intermediate hoppers or barges H, may be provided for interposition between a stern propulsion unit S and a hopper bow unit B as shown in FIG. 5. As will be seen the hopper H is of box type in that its ends 30, 31 are squared off so that it may be coupled either between a stern propulsion unit S and a hopper bow unit B, or to a dredger unit D for being filled with spoil from the dredging means.

I claim:

1. A system of waterborne units for dredging purposes comprising at least one dredger unit consisting of a relatively small self-powered and self-propelled vessel having normal ship form but with the forepart being square above the waterline, at least one stern propulsion and navigating unit consisting of a self-propelled vessel the forepart whereof terminates at a flat bulkhead, means for steering said stern propulsion and navigating unit, and at least two hopper bow units the aft ends whereof terminate in flat sterns, hinged coupling means detachably connecting said stern propulsion unit and one of 1y low powered and the propulsion means of said stern propulsion unit is relatively high powered whereby high transit speeds may be achieved during a dredging cycle.

3. A system of waterborne units, as claimed in claim 5, including at least one box-type hopper barge and means for interconnecting said box-type hopper barge to and between said stern propulsion unit and one of said hopper bow units.

* I t i t 

1. A system of waterborne units for dredging purposes comprising at least one dredger unit consisting of a relatively small selfpowered and self-propelled vessel having normal ship form but with the forepart being square above the waterline, at least one stern propulsion and navigating unit consisting of a selfpropelled vessel the forepart whereof terminates at a flat bulkhead, means for steering said stern propulsion and navigating unit, and at least two hopper bow units the aft ends whereof terminate in flat sterns, hinged coupling means detachably connecting said stern propulsion unit and one of said hopper bow units for being connected and navigated as a unitary vessel for the rapid disposal of spoil, and hinged coupling means detachably connecting the squared off bow of said dredger unit to the stern of the other of said hopper bow units so as to permit of the thus formed composite vessel being navigated and controlled appropriately for dredging operations.
 2. A system of waterborne units, as claimed in claim 1, wherein the propulsion means of said dredging unit is relatively low powered and the propulsion means of said stern propulsion unit is relatively high powered whereby high transit speeds may be achieved during a dredging cycle.
 3. A system of waterborne units, as claimed in claim 5, including at least one box-type hopper barge and means for interconnecting said box-type hopper barge to and between said stern propulsion unit and one of said hopper bow units. 